1. Field of the Invention
The present invention relates to an aluminum alloy sheet for high-speed forming and a process for manufacturing the same, and more particularly to an aluminum alloy sheet having excellent strength and ductility, having a good external appearance after forming, and having excellent high-speed formability with an average strain rate of 0.01 sec.sup.-1 and a process for obtaining the aluminum alloy sheet with high efficiency.
2. Description of the Related Art
Conventionally, a cold-rolled steel sheet has mainly been used as material for auto body sheets. However, there is an increasing demand for reduction in weight of an auto body, and using aluminum alloy sheets for material of auto outer panels.
In general, it is required that materials for auto body sheet have excellent press-formability and high strength. Aluminum alloy materials, which can meet these requirements, include JIS 5000-series Al--Mg---based alloys such as JIS 5052 alloy (Al--2.5 wt. % Mg--0.25 wt. % --0.25 wt. % Cr) and JIS 5182 alloy (Al--4.5 wt. % Mg--0.35 wt. % Mn).
Compared to a cold-rolled steel sheet, the JIS 5000-series aluminum alloy sheet has a lower ductility and is susceptible to cracking. In order to improve the ductility, various kinds of elements have been added or the amount of impurities has been reduced. However, at present, the ductility has not yet been enhanced.